The limited existing research comparing decomposition of native and non-native plants suggests that the leaves of non-native species decompose at a faster rate than those of native species. Non-native species are commonly used in horticultural landscaping and many have become common invaders of our forests, contributing significant amounts of biomass to the forest ecosystems. We compared decomposition rates of and communities of macro-organisms in leaf packs of 2 woody species common in forests of North Carolina, the native species Fagus grandifolia and the non-native Elaeagnus umbellata which is commonly invasive along the edges of forests and streams and in disturbed areas. Litter bags were filled with varied ratios of F. grandifolia and E. umbellata leaf biomass and placed in a streambed in the piedmont of North Carolina; half were collected after 6 weeks and the rest after 12 weeks.
Results/Conclusions
Litter bags containing 100% non-native leaf material had significantly less biomass remaining after 6 weeks than any of the bags that contained native leaves. After 12 weeks, there were no significant differences in the amount of leaf biomass remaining. There were greater numbers of macro-organisms found in leaf litter bags containing 100% native or 100% non-native leaves than in any combination treatment; an abundance of snails in these leaf packs was the primary driver behind this pattern.
The more rapid decomposition of E. umbellata leaves compared to those of F. grandifolia suggests more rapid nutrient cycling in forest ecosystems invaded by E. umbellata. Because the most common macro-organism in the leaf packs was similarly abundant with either species of leaf, the mechanism for the enhanced decomposition of non-native leaves remains unknown. Further research is needed to determine if this pattern holds for additional native and non-native species and to help determine the ways by which non-native species influence nutrient cycling in invaded forests.